CORDIS - EU research results

Inter-hemispheric Coupling of Abrupt Climate Change

Final Report Summary - INTERCLIMA (Inter-hemispheric Coupling of Abrupt Climate Change)

The primary goal of the InterClima project was to ‘advance understanding of the governing mechanisms and inter-hemispheric coupling involved in abrupt climate change’. Abrupt climate change refers to a transition in the climate system whose duration is fast relative to the duration of the preceding or subsequent state.
The three main objectives of InterClima were as follows: (1) to obtain precise estimates of the inter-polar phasing of past abrupt climate change events in ice cores from Antarctica and Greenland; (2) to expand out from the ice core records by using other plaeoclimate records to obtain a broader hemispheric view of the regional extent of past abrupt climate change events, particularly in the (less studied) Southern Hemisphere; and (3) to use the proxy climate data to test model simulations seeking to understand the mechanisms involved.

These objectives have been addressed in three high-impact papers.
1. WAIS Divide Project Members (including Pedro J.B.) 2015. Precise interpolar phasing of abrupt climate change during the last ice age,
Nature, doi:10.1038/nature14401.2014. (Journal IF 41.46).
In this paper we provide the most precise timing yet of the interpolar phasing of abrupt climate change during the last glacial period. We show that changes in climate trends in Antarctica lag abrupt climate variations in Greenland by 200 years.
2. Pedro, J.B. H.C. Bostock, C.M. Bitz, F. He, M. J. Vandergoes, E.J. Steig, B.M. Chase, C. E. Krause, S. O. Rasmussen, B. R. Markle and G. Cortese, 2016. The spatial extent and dynamics of the Antarctic Cold Reversal, Nature Geoscience, 9, 51-55, doi:10.1038/ngeo2580. (Journal IF 11.74.)

In this paper we compile data from 84 Southern Hemisphere palaeoclimate records (from ice, marine, and terrestrial archives). We then use the data synthesis to evaluate General Circulation Model experiments. We show that large-scale changes in meridional heat transport by the ocean and atmosphere are needed to explain the spatial extent and dynamics of past abrupt climate change events.
3. Pedro J.B. T.M. Martin, E.J. Steig, M. Jochum, W. Park and S.O. Rasmussen, 2016. Southern Ocean deep convection as a driver of Antarctic warming
events, Geophysical Research Letters, 43, doi:10.1002/2016GL067861.
(Journal IF 4.46).
In this paper we set out a new mechanism to explain past Antarctic warming events: heat release from Southern Ocean deep-convection coupled with albedo feedbacks and increased atmospheric heat transport to Antarctica.

Making well-informed decisions on how best to adapt to future climate change and how to mitigate the worst effects of climate change requires information on what the climate system is capable of. The InterClima project has improved our understanding of how abrupt climate change signals are communicated to different parts of the climate system: changes in meridional atmospheric heat transport drive abrupt climate variability in the southern hemisphere tropics and that slower ocean heat transport changes and sea ice feedbacks are more important in communicating abrupt climate change signals to the southern high latitudes.

Contact details: Joel Pedro, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen: